body {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
main {
  max-width: 800px;
  margin: 0 auto;
}
h1 {
  text-align: center;
  font-size: 2.5rem;
  color: blue;
}
button:hover {
  font-size: 1.1rem;
  padding: .6rem;
  color: green;
}
img {
  width: 100%;
}
#name {
  color: lightsalmon;
}
.skyblue {
  color: skyblue;
}

div.demo {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 999;
  background-color: rgba(0,0,0,0.8);
  display: grid;
  place-items: center;
}
div.dialog {
  width: 10rem;
  height: 6rem;
  background-color: white;
  display: grid;
  place-items: center;
}
section.navbar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: 3rem;
  z-index: -1;
  background-color: green;
  display: flex;
  justify-content: space-around;
  align-items: center;
}

section.content {
  background-color: whitesmoke;
}